Younger postmenopausal women may not get enough calcium

Low calcium intake was common among patients vulnerable to bone loss, including women receiving endocrine therapy for breast cancer.

A recent study published in the journal Nutrients suggests that younger postmenopausal women evaluated for bone fragility and women at high risk of osteoporosis and fragility fractures may be consuming less calcium than recommended in Italy. In this study, the average calcium consumption also remained below the recommended level among women receiving adjuvant endocrine therapy (AET) for breast cancer (BC). Together, these findings emphasize the need for more nutritional counseling and awareness to improve calcium intake among women at risk of, or living with, osteoporosis.

Calcium intake falls short in women already facing bone-loss risks

Milk and dairy products are the main dietary sources of calcium, followed by vegetables, seafood, dried fruits, cereals, plant-based milks, and calcium-rich waters. Based on recommendations from the Italian Society for Osteoporosis, Mineral Metabolism and Skeletal Diseases (SIOMMMS), postmenopausal women receiving hormone replacement therapy and men 50 to 65 years of age should consume 1,000 mg/day.

Higher intake of 1,200 mg/day is recommended for postmenopausal women who are not receiving such therapy and men aged above 65 years. An investigation into daily calcium intake among postmenopausal women and women receiving AET is required to assess dietary habits and improve public awareness.

How researchers measured calcium intake and bone health

In the present study, researchers evaluated calcium consumption among patients referred for assessment of bone metabolism and fracture risk. The primary focus was breast cancer (BC) patients receiving adjuvant endocrine therapy (AET) who are prone to developing secondary osteoporosis.

The team collected data from 122 females and 10 males evaluated at the Division of Endocrinology, Azienda Ospedaliero-Universitaria delle Marche, Italy, between January 2020 and December 2021. Participants were referred to the Osteoporosis and Bone Metabolism Diseases outpatient clinic for assessment.

Using a food frequency questionnaire (FFQ), the researchers assessed dietary intake over seven days. The questionnaire was based on the International Osteoporosis Foundation (IOF) Calcium Calculator and validated by SIOMMMS.

The researchers also recorded all study participants' comorbidities, previous fragility fracture events, osteoporosis etiology, and densitometric and biochemical parameters. Researchers also collected available blood measurements related to calcium and bone metabolism, including serum calcium, phosphorus, parathyroid hormone (PTH), 25-OH-cholecalciferol (25(OH)D), bone alkaline phosphatase (bALP), and C-terminal telopeptide of type 1 collagen (CTX). To assess variability in calcium consumption among participants, the team explored the impact of sex, age, pharmacological treatments, bone mineral density (BMD), and trabecular bone score (TBS).

Dual-energy X-ray absorptiometry (DXA) scans determined BMD at the lumbar spine and proximal femur. Researchers identified vertebral fractures using quantitative vertebral morphometry from DXA or morphometric thoracolumbar radiography, while anamnesis and previous evaluations helped identify non-vertebral fractures.

Fragility fractures were defined as those occurring without sufficiently severe trauma to explain the fracture. Fractures considered minor osteoporotic fractures did not affect the vertebrae, femur, forearm, or proximal humerus, and included those affecting the clavicle, ribs, tibia, fibula, and pelvis.

Calcium shortfalls appear across several higher-risk groups

Women accounted for 92% of participants, and all were either postmenopausal or undergoing ovarian suppression because of AET. The overall cohort had a mean age of 65 years. Over 43% had severe osteoporosis with at least one fragility fracture, nearly 41% were at an increased risk of developing the condition.

Approximately 65% of patients evaluated for secondary osteoporosis were receiving AET for breast cancer. On average, participants consumed 959 mg of calcium daily.

Younger women with postmenopausal osteoporosis had a lower daily calcium intake, averaging 848 mg. Those with normal BMD averaged 631 mg/day. Participants with no fragility fractures consumed 906 mg daily, while those undergoing assessment for secondary osteoporosis consumed 900 mg.

Breast cancer patients on endocrine therapy show another calcium gap.

Among women receiving AET, average intake was 854 mg/day, which is similarly below recommended levels. Twenty-seven of the 35 women in this subgroup, or 77.1%, consumed less calcium than recommended. This is particularly relevant to bone health because some AET drugs reduce estrogen production, whereas others modulate estrogen receptor (ER) signaling. Estrogen supports bone formation through osteoblast activity and limits bone resorption by osteoclasts.

The study did not examine reasons for low calcium intake among women receiving AET. The authors proposed that concerns about dairy consumption could contribute, but described this explanation as a hypothesis, rather than a study finding.

Dietary calcium intake was below recommended Italian thresholds in this cohort of patients at high risk of osteoporosis and fragility fractures. These findings may be especially relevant since BC accounts for a substantial proportion of cancer-related mortality among women worldwide, and ER-positive breast cancers are commonly treated with AET, which can affect estrogen signaling.

Although AET may improve survival outcomes, it has also been associated with an increased risk of osteoporosis and fractures.

What the findings mean for bone-health counseling

Several limitations restrict how broadly the findings can be interpreted. The study was cross-sectional and conducted at a single center, subgroup sizes were small, and no multivariable analysis was performed. Therefore, the reported associations should be regarded as hypothesis-generating.

The researchers also could not calculate total calcium intake because calcium supplement doses were unavailable. In contrast, information on vitamin D doses, AET duration, time since breast cancer diagnosis, cancer stage, recurrence, and glucocorticoid exposure was incomplete or unavailable.

Greater nutritional counseling and awareness could help patients at risk of osteoporosis meet recommended calcium requirements. The authors recommend individualized nutritional assessment and counseling to help patients meet calcium requirements through suitable dietary sources, including selected low-fat and fermented dairy products and, when appropriate, alternative calcium sources. These findings need confirmation in multicenter prospective studies with larger populations, while accounting for vitamin D supplementation, cancer staging, recurrence status, and glucocorticoid exposure. Further studies should also examine why calcium intake differs between patient groups.

Journal reference:

• Firmani, F., Ciarloni, A., Sabatelli, S., et al. (2026). Dietary Calcium Intake in Patients Evaluated for Bone Fragility, with a Focus on Women Receiving Adjuvant Endocrine Therapy for Breast Cancer: A Single-Center Cross-Sectional Study. Nutrients 18(19), 3239. DOI: 10.3390/nu18193239. https://www.mdpi.com/2072-6643/18/19/3239